756 879 123 - 16 10.Feral rabbit, Porto Santo: 2.95 .. .. 835 910 75 - 9 Average of three Porto Santo rabbits: 2.88 .. .. 828 888 60 - 7
11.Himalayan: 3.5 20.5 .. 963 1080 117 - 12
12.Moscow: 3.25 17.0 3,8 803 1002 199 - 24
13.Angora: 3.5 19.5 3,1 697 1080 383 - 54
14.Chinchilla: 3.65 22.0 .. 995 1126 131 - 13
15.Large lop-eared: 4.1 24.5 7,0 1065 1265 200 - 18 16.Large lop-eared: 4.1 25.0 7,13 1153 1265 112 - 9 17.Large lop-eared: 4.07 .. .. 1037 1255 218 - 21 18.Large lop-eared: 4.1 25.0 7,4 1208 1265 57 - 4 19.Large lop-eared: 4.3 .. .. 1232 1326 94 - 7 20.Large lop-eared: 4.25 .. .. 1124 1311 187 - 16 21.Large hare-coloured: 3.86 24.0 6,14 1131 1191 60 - 5 22.Average of above seven large lop-eared rabbits: 4.11 24.62 7,4 1136 1268 132 - 11
23.Hare (L. timidus) English specimen: 3.61 7,0 1315
24.Hare (L. timidus) German specimen: 3.82 7,0 1455
In the upper half of Table 3 I have given the measurements of the skull of ten wild rabbits; and in the lower half, of eleven thoroughly domesticated kinds. As these rabbits differ so greatly in size, it is necessary to have some standard by which to compare the capacities of their skulls. I have selected the length of skull as the best standard, for in the larger rabbits it has not, as already stated, increased in length so much as the body; but as the skull, like every other part, varies in length, neither it nor any other part affords a perfect standard.
In the first column of figures the extreme length of the skull is given in inches and decimals. I am aware that these measurements pretend to greater accuracy than is possible; but I have found it the least trouble to record the exact length which the compass gave. The second and third columns give the length and weight of body, whenever these observations were made. The fourth column gives the capacity of the skull by the weight of small shot with which the skulls were filled; but it is not pretended that these weights are accurate within a few grains. In the fifth column the capacity is given which the skull ought to have had by calculation, according to the length of skull, in comparison with that of the wild rabbit No. 1; in the sixth column the difference between the actual and calculated capacities, and in the seventh the percentage of increase or decrease, are given. For instance, as the wild rabbit No. 5 has a shorter and lighter body than the wild rabbit No. 1, we might have expected that its skull would have had less capacity; the actual capacity, as expressed by the weight of shot, is 875 grains, which is 97 grains less than that of the first rabbit. But comparing these two rabbits by the length of their skulls, we see that in No. 1 the skull is 3.15 inches in length, and in No. 5 2.96 inches in length; according to this ratio, the brain of No. 5 ought to have had a capacity of 913 grains of shot, which is above the actual capacity, but only by 38 grains. Or, to put the case in another way (as in column VII), the brain of this small rabbit, No. 5, for every 100 grains of weight is only 4 grains too light,--that is, it ought, according to the standard rabbit No. 1, to have been 4 per cent heavier. I have taken the rabbit No. 1 as the standard of comparison because, of the skulls having a full average length, this has the least capacity; so that it is the least favourable to the result which I wish to show, namely, that the brain in all long-domesticated rabbits has decreased in size, either actually, or relatively to the length of the head and body, in comparison with the brain of the wild rabbit.